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Advances in Materials Science and Engineering
Volume 2015, Article ID 286469, 5 pages
http://dx.doi.org/10.1155/2015/286469
Research Article

Nondestructive Testing of Advanced Concrete Structure during Lifetime

Brno University of Technology, Veveri 95, 602 00 Brno, Czech Republic

Received 19 September 2014; Revised 1 December 2014; Accepted 18 December 2014

Academic Editor: Yan Yang

Copyright © 2015 Lubos Pazdera et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The paper reports on measurements and analysis of the measurements during hardening and drying of specimens using selected acoustic nondestructive testing techniques. An integrated approach was created for better understanding of the relations between the lifetime cycle and the development of the mechanical properties of concrete. Acoustic emission, impact echo, and ultrasonic techniques were applied simultaneously to the same mixtures. These techniques and results are presented on alkali-activated slag mortars. The acoustic emission method detects transient elastic waves within the material, caused by the release of cumulated stress energy, which can be mechanical, thermal, or chemical. Hence, the cause is a phenomenon which releases elastic energy into the material, which then spreads in the form of an elastic wave. The impact echo method is based on physical laws of elastic stress wave propagation in solids generated by mechanical impulse. Ultrasonic testing is commonly used to find flaws in materials or to assess wave velocity spreading.